Field of the Invention
The present invention relates to a cleaning blade, an image forming apparatus, and a process cartridge.
Description of the Related Art
Conventionally, electrophotographic image forming apparatuses remove residual toner deposited on the surface of an image bearing member after having transferred a toner image onto a recording medium or an intermediate transfer medium in an image forming step, with a cleaning unit.
A cleaning blade is used as the cleaning unit because a cleaning blade has a simple structure and is excellent in cleaning performance. The cleaning blade is typically constituted by an elastic member made of polyurethane rubber or the like, and a support member. With a base end of the elastic member supported on the support member, an abutment part (a leading end edge portion) of the elastic member is thrust against the surface of the image bearing member, in order for the residual toner on the surface of the image bearing member to be removed by being banked up and scraped off.
However, as shown in FIG. 1A, a frictional force between the image bearing member 123 and the cleaning blade 62 made of polyurethane rubber may increase to drag the cleaning blade 62 in the moving direction of the image bearing member 123 and make the abutment part (the leading end edge portion) 62c of the cleaning blade 62 ride up. Further, if the cleaning is continued with the abutment part 62c of the cleaning blade 62 ridden up, a local wear X may occur at a location of a leading end surface 62a of the cleaning blade 62 that is several μm away from the abutment part 62c, as shown in FIG. 1B. If the cleaning is further continued in this state, the local wear X may become larger to finally drop off the abutment part 62c, as shown in FIG. 1C. If the abutment part 62c is dropped off in this way, it is no longer possible for toner to be cleaned away properly, leading to a problem that a cleaning failure occurs. Note that the reference numeral 62b in FIG. 1A to FIG. 1C denotes a lower surface of the cleaning blade.
Hence, there has been an attempt to make the abutment part safe from deformation by enhancing the hardness thereof in order to suppress the riding up of the abutment part (the leading end edge portion) of the cleaning blade that is to abut on the surface of the image bearing member. For example, there are proposals to provide a surface layer containing an ultraviolet-curable resin over the abutment part of the cleaning blade or the elastic member to enhance the hardness of the abutment part, to thereby prevent riding up or deformation of the abutment part (see Japanese Patent (JP-B) No. 3602898, and Japanese Patent Application Laid-Open (JP-A) Nos. 2004-233818 and 2010-152295).
However, the ultraviolet-curable resin used in these proposals has a high crosslink density. Therefore, when the surface layer provided over the abutment part is cured, it undergoes large cure shrinkage, leading to a problem that the surface layer cracks or the surface layer peels.
Hence, it is requested to provide a cleaning blade that can suppress an abutment part of an elastic member thereof to abut on the surface of a cleaning target member from riding up, that has little wear over the abutment part of the elastic member during use, and that can maintain favorable cleaning performance for a long term.